The use of light emitting diodes in general lighting is still limited due to limitations in light output level or flux generated by the illumination devices due to the limited maximum temperature of the LED chip, and the life time requirements, which are strongly related to the temperature of the LED chip. The temperature of the LED chip is determined by the cooling capacity in the system, and the power efficiency of the device (optical power produced by the LEDs and LED system, versus the electrical power going in). Illumination devices that use LEDs also typically suffer from poor color quality characterized by color point instability. The color point instability varies over time as well as from part to part. Poor color quality is also characterized by poor color rendering, which is due to the spectrum produced by the LED light sources having bands with no or little power. Further, illumination devices that use LEDs typically have spatial and/or angular variations in the color. Additionally, illumination devices that use LEDs are expensive due to, among other things, the necessity of required color control electronics and/or sensors to maintain the color point of the light source or using only a selection of LEDs produced, which meet the color and/or flux requirements for the application at the time the LEDs are selected.
Consequently, improvements to illumination devices that uses light emitting diodes as the light source are desired.